Hamas will likely be able to expand the range of its homemade rockets to 20 kilometers by the end of the year, an Israel security official said Thursday. Such an upgrade could give Hamas an unlimited supply of rockets for targeting the Israeli coastal city of Ashkelon, which is 17 kilometers from Gaza and has 110,000 residents, military analysts said. Currently, Hamas uses smuggled military-issue Iranian rockets, of which it has a limited supply, to take occasional aim at Ashkelon. Four such rockets hit the southern part of the city Wednesday, including one that fell in the parking lot of a hospital, as part of an escalation in Israel-Gaza cross-border fighting that has killed 23 Palestinians and an Israeli man in the past two days. The IDF said Hamas's rockets, which started out with a range of 7-8 kilometers in 2001, now have a reach of up to 16 kilometers. The rockets are widely referred to as Kassams because they were developed by Hamas's militant group's military wing, Izzedine al Kassam. "We are doing our best to upgrade our capabilities," said Abu Obeida, a spokesman for Izzedine al Kassam. "We will never have equipment comparable to our enemy, but we are working all the time to have enough to make any aggression a regrettable adventure for the enemy." In recent years, Hamas has fired hundreds of rockets at the Israeli border town of Sderot, just 2 kilometers from Gaza. As part of an escalation of cross-border fighting, Hamas fired scores of rockets Wednesday, including one that killed a 47-year-old man at a community college in Sderot. At the same time, 23 Palestinians, including many terrorists, but also a baby, were killed over two days by Israeli missile strikes. A senior Israeli security official, speaking on condition of anonymity as part of briefing regulations, said Thursday that Hamas's rockets will reach deeper into Israel in coming months. "We think that until the end of this year, they (Hamas terrorists) will reach a range of 20 kilometers with Kassams, not with military-issue rockets," he said. Hamas currently has an inventory of hundreds of Kassams, he said. The official said Hamas's military wing in Gaza has a budget of up to $30 million a year, including weapons production, salaries and preparing attacks on Israel. He said up to one-third of the money comes from Iran, and the rest from donations and other sources. The official said Hamas is manufacturing not only rockets, but also explosive devices and bullets, describing the enterprise as a "military industry, not very advanced, but existing."